Modern data processing systems may have many attached remote peripheral units, numbering in the tens, or more. Each of these remote units may be the source of an interrupt that the operating system (OS) must isolate and handle. Moreover, it is the nature of most interrupts that they require immediate attention. For example, a peripheral device may monitor its environment, and generate an interrupt if an environmental problem, such as over temperature, fan loss or power loss occurs. These environmental problems may require immediate attention in order to preserve data integrity, and prevent the hardware from becoming permanently damaged.
Interrupt isolation mechanisms examine each of the attached peripheral units. The operating system traverses the attached peripheral units until a device having a set interrupt register is found Having thus isolated the source of the interrupt, the OS can service the interrupt. Having to examine each of the attached peripheral units, until the interrupt source is found can introduce a significant delay in overall data processing system speed. Thus, there is a need in the art for apparatus and methods to reduce the time needed to isolate interrupt sources, and thereby improve the handling of interrupts.